Technical Abstract:
Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environmental-friendly lubricants. Vegetable oils have excellent lubricity, but poor oxidation and low-temperature stability. This paper presents a series of structural modifications of vegetable oils using anhydrides of different chain lengths. The reaction was monitored and products were confirmed by NMR, FTIR, gel permeation chromatography, and thermogravimetric analysis (TGA). Experimental conditions were optimized for research quantity and for laboratory scale-up (up to 4 lb = 1.8 kg). The thermo-oxidation stability of these new lubricant base fluids was tested using pressure differential scanning calorimetry and TGA. The chemically modified base fluids exhibit superior oxidation stability in comparison with unmodified vegetable oils. These base fluids in combination with suitable additives exhibit equivalent oxidation stability compared with mineral oil-based formulations.